A retrospective study of the changing trends of antimicrobial resistance of Klebsiella pneumoniae isolated from urine samples over last 3 years (2012-2014)

Biofilm Formation and Associated Gene Expression in Multidrug-Resistant Klebsiella pneumoniae Isolated from Clinical Specimens

Biofilms reduce the bacterial growth rate, inhibit antibiotic penetration, lead to the development of persister cells and facilitate genetic exchange. The biofilm-associated Klebsiella pneumoniae infections have not been well studied, and their implications in overcoming the effects of antimicrobial therapy are yet to be fully understood. Hence this study evaluated the antibiotic resistance pattern, antibiotic resistance determinants of extended-spectrum beta-lactamase (ESBL) family. Biofilm-forming ability of seventy multidrug-resistant clinical isolates of K. pneumoniae and the biofilm-associated genes of representative biofilm formers from a tertiary care hospital were also assessed. The K. pneumoniae isolated from urine exhibited resistance towards ceftazidime, nalidixic acid and meropenem. Isolates from blood were resistant to cefuroxime. Higher rates of resistance were observed towards cefuroxime, nalidixic acid, and meropenem for the isolates from the endotracheal aspirate. Extended spectrum beta-lactamase production by CLSI's disc diffusion-based confirmation test revealed all the K. pneumoniae to be as ESBL producers. Most of the isolates harboured the bla gene variants, bla_SHV and bla_TEM. Majority of the isolates were colistin sensitive. 97.1% of the K. pneumoniae produced biofilm. K. pneumoniae isolated from pus and blood produced fully established biofilms. Strong biofilm formers were sensitive to co-trimoxazole and ciprofloxacin. Moderate biofilm formers exhibited sensitivity towards meropenem and imipenem. Expression of the fimH gene was increased, while mrkD showed reduced expression among the strong biofilm formers. Moderate biofilm formers showed variable expression of the genes associated with the biofilm formation. The weak and non-biofilm formers showed reduced expression of both the fimbrial genes. Multidrug-resistant isolates produced ESBLs and formed well-established biofilms.

Retrospective study on clonal relationship of multidrug-resistant Klebsiella spp. indicates closed circulation and initiation of clonal divergence

PURPOSE

Antibiotic resistance patterns often exhibit geographical variations. Periodic analyses of resistance spectra and phylogenetic trends are important guides for facilitating judicious use of therapeutic interventions. The present study retrospectively analysed the infection trends, resistance patterns, and clonal relationships between isolates of Klebsiella spp. from a tertiary care hospital.

METHODOLOGY

Bacterial isolates were collected from January 2013 to June 2014 and their resistance profiles were identified using an automated bacterial identification system. A phylogenetic tree was constructed using housekeeping genes with Molecular Evolutionary Genetic Analysis software. The dN/dS ratio was determined by the Synonymous Non-synonymous Analysis Program while polymorphic sites, and the difference per site was calculated using DNA Sequence Polymorphism software. Statistical Package for Social Science software was used to perform all statistical analyses.

KEY FINDINGS

The results of this study indicated the prevalence of community-acquired urinary tract and lower respiratory tract infections caused by Klebsiella spp. among geriatric patients. The occurrence of new allelic profiles, a low dN/dS ratio and the lack of strong evolutionary descent between isolates indicated that mutations play a major role in the evolution of the organism.

CONCLUSION

The findings of this study highlight the consequences of antimicrobial agents exerting a silent and strong selective force on the evolution of Klebsiella spp. The expansion of such analyses is of great importance for addressing rapidly emerging antibiotic-resistant opportunistic pathogens.

Trends in Resistance to Extended-Spectrum Cephalosporins and Carbapenems among Escherichia coli and Klebsiella spp. Isolates in a District in Western India during 2004-2014

Surveillance data on the level of resistant bacteria is needed to inform strategies to reduce the development and spread of antibiotic resistance. The aim of this study was to determine the non-susceptibility trends to extended-spectrum cephalosporins and carbapenems among Escherichia coli and Klebsiella spp. isolates from the district of Nashik in Western India during the period 2004-2014. Antibacterial susceptibility testing of clinical isolates was performed using Kirby-Bauer disc diffusion method to determine inhibitory zone diameters. The change in proportions of non-susceptible bacteria over calendar time was investigated with spline transformations in a logistic regression model. For the extended-spectrum cephalosporins, the proportions of non-susceptible E. coli and Klebsiella spp. isolates were above 78.4% and 84.9% throughout the study period, respectively. E. coli and Klebsiella spp. isolates exhibited carbapenem non-susceptibility levels as high as 76.9% and 84.1% respectively. The proportions of extended-spectrum betalactamase (ESBL)-producing isolates ranged from 38.3-85.9% in E. coli and from 45.1-93.1% in Klebsiella spp. Significantly higher proportions of non-susceptible and ESBL-producing isolates were found among isolates from inpatients compared to isolates from outpatients for both E. coli and Klebsiella spp. (p < 0.050). The high proportions of non-susceptible isolates observed show that there is great need to focus on optimal use of antibiotics to reduce the development of antibiotic resistance.